This is a proposal to study three particular cell types in the rabbit retina, each of which has a well-defined dendritic morphology and whose dendrites all ramify in the same two sublaminae within the inner plexiform layer. Starburst amacrine cells contain both acetylcholine and GABA and are known to interact with ON-OFF directionally-selective ganglion cells. A third cell type, the so-called DAPI-3 cell, receives both cholinergic and GABAergic input and may be involved in a feedback loop with the starburst amacrine cells via glycinergic transmission. The circuitry between these cell types involves both nicotinic and muscarinic acetylcholine receptors, GABA-A receptors, GABA-B receptors, and glycine receptors. The premise of this proposal is that by defining the synaptic circuitry between these cells, and by localizing the different receptor subtypes, it will be possible to approach an understanding of how neuronal microcircuitry translates into physiological function.